Apparatus and process for forming yarns and other twisted assemblies



1366- 2 1965 D. E. HENSHAW APPARATUS AND PROCESS FOR FORMING YARNS AND OTHER TWISTED ASSEMBLIES 4 Sheets-Sheet 1 Filed Oct. 18, 1962 Dec. 28, 1965 D. E. HENSHAW 3,225,533

APPARATUS AND PROCESS FOR FORMING YARNS AND OTHER TWISTED ASSEMBLIES Filed Oct. 1.8, 1962 4 Sheets-Sheet 2 1965 D. E. HENSHAW APPARATUS AND PROCESS FOR FORMING YARNS AND OTHER TWISTED ASSEMBLIES 4 Sheets-Sheet 3 Filed Oct. 18, 1962 Dec. 28, 1965 D. E. HENSHAW APPARATUS AND PROCESS FOR FORMING YARNS AND OTHER TWISTED ASSEMBLIES 4 Sheets-Sheet 4 Filed Oct. 18, 1962 United States Patent 3,225,533 APPARATUS AND PROCESS FOR FORMHNG YARNS AND OTIER TWISTED ASSEMBLlES David Ernest Henshaw, Geelong, Victoria, Australia, as-

signor to Commonwealth Scientific and Industrial Research Organization, Melbourne, Victoria, Australia, a body corporate Filed Oct. 18, 1962, Ser. No. 231,457 Claims priority, application Australia, Oct. 19, 1951,

10,441/61; Jan. 16, 1962, 13,360/62 22 Claims. (Cl. 57-34) This invention relates to the formation of twisted fibre assemblies by spinning and is applicable particularly but not exclusively to spinning of yarn from staple fibres, for example wool fibres. Other applications of the invention include its use in the earlier stages of yarn production for example in drawing operations.

In conventional staple fibre spinning processes, fibres which have previously been formed into sliver are subjected to a number of drawing operations to produce a roving. The roving is spun into yarn by machines which draft the roving and insert continuous twist into it and wind the resultant yarn on to a package. For convenience of description of these conventional processes, since we are considering particularly a process which converts roving into yarn, the term roving will be used to describe the fibre assembly put into the spinning machine and the output will be called a yarn. The most common spinning machines are cap spinning machines and ring spinning machines each of which cause twist to be inserted into the yarn as it is wound on to a rapidly rotating spindle. In each case the yarn is wound over the end of the spindle and the spindle must rotate at a speed much higher than that required to wind the yarn on to the package in order to insert the twist into the yarn. In consequence, the speed of rotation of the spindle is a controlling factor in the output of the machine which has tended to limit the production rate of conventional machines. Yarn travelling to the rapidly rotating spindle is caused to balloon by the relatively high centrifugal forces acting on the yarn as it is rotated. These forces together with other forces such as that due to air resistance on the yarn lead to relatively high tensional forces being imposed on the yarn.

The spinning processes above referred to also suffer from other disadvantages including the following:

(1) The rate at which twist can be inserted into the yarn is limited by the rate at which the package can be rotated.

(2) The tensional forces above referred to set a practical upper limit to production rate and a lower limit to the weight per unit length of the yarn which can be produced (to avoid end breaks).

(3) Because of the existence of balloon tensions and centrifugal forces the packages of yarn formed are limited in size and type so that rewinding of the yarn is usually necessary before use.

(4) The entire machine must be stopped in order to replace full packages.

There are other spinning processes which overcome some of the above disadvantages but these other processes are not so extensively used and have themselves certain inherent disadvantages.

Similar problems are encountered in the earlier stages of yarn production such as the production of rovings where the sliver or roving as the case may be is subjected to a number of successive drawing operations. During these operations the fibre assembly is either twisted or rubbed to consolidate the fibres and also to impart some strength to the assembly to assist in transport of the assembly from package to machine and from machine to 3,225,533 Patented Dec. 28, I965 package. This is usually done by twisting (for example, by using a flyer) or by rubbing (for example between belts in a continental drawing system). Twisting is usually done by a mechanism which in principle is substantially similar to a spinning frame and the three abovementioned disadvantages are present. In addition, in the case of rovings, the following further problems arise:

(5) The yarn weight is greater and the package size is larger so that the packages must be rotated at lower speeds.

(6) The existence of the real twist in the roving is often undesirable in subsequent operations.

The rubbing method also has disadvantages which include the following:

1) Limitation in production rate due to the necessity of moving a heavy rubbing mechanism transversely, usually with an oscillatory motion.

( 2) Lack of strength in the rubbed assemblies of fibres.

(3) The method cannot be used for slivers of high weight per unit length.

4) It is a disadvantage in subsequent drawing to have the fibre disorientation caused by rubbing. For example, in a subsequent gilling operation such disorientation will produce fibre breakage and incorrect drafting.

(5) End breaks are often caused by the rubbing device.

This invention aims to provide a process for the production of a twisted fibre structure, in which the above problems are eliminated or at least substantially reduced. In particular it is the object of the invention to provide a process in which it is not necessary, in order to impart the twist, to rotate the take-up package at high speed. Thereby it is hoped that a twisted assembly can be produced at high production rates without frequent breakages and that the assembly can be taken up on a package suitable for use in later processing.

Since the following description will refer to many different types of structure such as rovings, slivers and yarns of both staple and continuous filament, multiand monofilament construction, the word thread will hereafter be employed to connote all such structures and other similar structures.

The basic problem in the production of twisted threads lies in the necessity for inserting the twist by winding over the end of rapidly rotating packages. False twist can be inserted into a travelling thread without the ne cessity for rapid rotation of the take-up package and it can be shown that by making the twisting intermittent an output thread which has twist in it can be produced. Such a thread will have along its length alternating zones of opposite twist. However the twist in such a thread is unstable and the twist will disappear if the thread is unsupported over the length of two adjacent zones of opposite twist. These propositions may be illustrated by the following example:

Consider a thread travelling between two nip positions to a take-off package. If, at some intermediate point the thread is twisted as it travels, the thread on the rear side of the twist point will have, say, S twist and the thread on the other side of the twist point will have Z twist. However, since the thread is travelling, thread having S twist will be carried past the twist point and it will tend to cancel out the Z twist being inserted into the thread in front of the twist point until ultimately equilibrium is achieved when there is practically no twist in the thread which is issuing from the twist point.

If the thread is twisted not continuously but intermittently, the condition of no twist in the thread immediately in front of the twist point is not reached. The travelling thread is twisted so that there is, say, S twist behind the twist point and Z twist in front of it. A section of thread is thus produced which has Z twist at the front, a transition zone of no twist and S twist at the rear. Since the thread is a travelling thread the Z twist section is taken on to the take-ofi package. If now, twisting is temporarily interrupted and the thread at the twist point released, S twist thread will pass through the twist point to the takeoff package. Twisting is recommended and Z twist thread is again produced and passed to the take-off package and so on. Thus the thread taken off by the take-off package has alternating zones of S and Z twist.

Examples of the utilization of this form of twisting are in the output head of some gilling machines where the output sliver is given an alternating twist just before it is wound onto the take-up package and in the process described in British patent specification 878,671. Another example of the use of alternating twist is in the production of the yarn described in French patent specification No. 1,150,847 wherein alternating twist is inserted into a yarn and the twist is stabilized either by thermosetting the yarn or by applying a settable size solution to it. Still further examples of alternating twisting techniques are shown in French patent specification No. 701,689 wherein an alternating doubling twist is used to produce a novelty yarn by combining two or more yarns, and in Australian patent specification Nos. 224,281, 238,109 and 238,260 and in US. patent specification No. 2,990,671 wherein alternating twists are used to form interlaced yarns by the vortex twisting technique. In this later case the twist is stabilized by thermosetting, by the use of a settable size or by the more or less random intertwining of the individual fibres in the yarn. Still further applications are to be found in processes in which a yarn, a roving or some other fibre assembly is alternately twisted and the twist in the assembly is restrained by ensuring that the twisted assembly is supported in such a way as to restrain the twist for example by winding it onto a package or incorporating it into a fabric in such a way that the assembly is not free over a length greater than about that of one twist zone.

In any case where alternating twist is inserted into a yarn the twist must be stabilized in some way or another otherwise the twist from one region will run into the adjacent oppositely twisted region and the two twist will cancel out. Even in cases where the fibres are such that they have a tendency to retain their twisted condition this will occur when tension is applied unless the twist is somehow stabilised.

This invention resides in forming a thread having alternating zones of opposite twist and stabilising the twist by bringing the thread so twisted together with another thread and allowing it to twist around the other thread. Conveniently two or more threads each with zones of alternating twist, may be brought together with their twist zones in suitable phase relationship and allowed to twist around each other to achieve stabilization.

If a thread which has a restrained torque in it is brought together with another thread and the torque restraint is released, the thread having the torque in it will tend to unwind and in so doing will wrap itself around the other thread. When this happens, the torque remaining in the thread will again be restrained by virtue of the wrapping. A thread which has alternating zones of opposite twist in it will wrap in alternating opposite directions according to the alternation of the twist originally inserted into the thread. In the case where both threads, or all of them if there are more than two, are intermittently twisted, and provided that the regions of twist in the threads are suittably phased, when the threads commence to untwist they twist around each other. This plying of the threads restrains the twist in each individual thread and results in a self-stabilised plied assembly. Such an assembly will hereafter, for the sake of convenience, be called a selftwist thread or, where appropriate, more specifically, a self-twist yarn or a self-twist roving and the individual components will be called strands.

If two strands which are each individually twisted in the same sense are brought together and allowed to untwist they will, in doing so, wrap around one another. However, if the strands have twists in opposite senses they will not wrap together. Thus in accordance with this invention the zones of alternating twists in strands which are brought together are phased so that zones having twists in the same sense at least partly coincide. In the plied structure the individual strands which have zones of alternating twist unite to form the plied thread which itself has zones of alternating twist.

In the case of a spun staple fibre assembly strength is: imparted to the structure by the twist because the fibres are laid up on one another in a helical form. In the case of an intermittently twisted thread having equal zones of alternating twist there will be, between each twistzone, a twist change-over region where there is no twist. If two strands so formed are brought together to form a selftwist thread with their twist zones exactly in phase, then the regions of no twist in the two strands will coincide and furthermore the twist change-over region, or region of no twist, in the plied structure will coincide with them. These twist change-over regions will therefore constitute points of weakness since there there will be no twist either in the self-twist thread or its individual components. Such a thread may have sufiicient strength for some purposes but where a thread of substantial strength is required, for example in a worsted yard, these regions of weakness are, in accordance with another aspect of the invention, strengthened. This is done by bringing the twisted strands together so that their twist change-over regions are out of phase. The result of this is that the regions of no twist in the plied structure and in each individual component no longer coincide so that at all points in the structure there is some twist to give it strength and consolidation.

The invention will now be more fully described with reference to its use in the production of yarn from rovings of wool fibre. An example of apparatus for use in accordance with the invention is shown in the accompanying drawings in which:

FIGURE 1 is a schematic side elevation of the apparatus,

FIGURE 2 is a schematic plan view,

FIGURE 3 is a detailed plan view on a larger scale of the mechanism for twisting and converging the strands,

FIGURE 4 is an enlarged side View corresponding to FIGURE 3,

FIGURE 5 is an enlarged view of the twisting device looked at from the front from the line 55 in FIG- URE 4,

FIGURE 6 is a detailed plan view of the take-up rollers and yarn guide shown in FIGURES 1 to 4,

FIGURE 7 is a sectional view on line 77 in FIG- URE 6,

FIGURE 8 is a view similar to FIGURE 1 but showing alternative drafting, twisting and take-up roller arrangements,

FIGURE 9 is a schematic plan view of the apparatus: shown in FIGURE 8,

FIGURE 10 is a detailed sectional view of one of the twister tubes shown in FIGURES 8 and 9,

FIGURE 11A is of diagrammatic representation of a self twist yarn formed of two intermittently twisted strands with their twist zones of equal length and in phase,

FIGURE 11B is a hypothetical graphic illustration of the twist distribution in the strands and the yarn shown in FIGURE 11A,

FIGURE 12A is a representation similar to FIGURE 11A with the twist zones of the strands partly out of phase,

FIGURE 12B is a hypothetical graphic illustration of the twist distribution of the structure shown in FIGURE 12B,

FIGURE 13A is a representation of a construction in which in each strand the twist zones are alternately long and short and in which the zone lengths in each strand are complementary,

FIGURE 13B is a hypothetical graphic illustration of the twist distribution of the structure shown in FIGURE 13A, and

FIGURE 14 is a graph showing a typical variation of yarn strength with twist zone phasing in a two strand self-twist yarn.

In the apparatus shown in FIGURES 1 to 7, roving 1 is drawn from packages 2 and fed through a conventional apron drafting mechanism 3 where it is attenuated. According to the nomenclature used herein the output from the front rollers 4 of the drafting mechanism is a strand 5 which passes past a twist length compensating device 6 and thence through further guide means 7 to a twisting device 8. The twisting device 8 consists of a large central disc 9 and two side discs 10. The central disc 9 has on each side generally part annular rubber surfaces, 11, 11a, each of which extends about half way around the periphery of the disc. The side discs each have a complete rubber annulus 12 on the side adjacent the central disc. It will also be observed that the axes of the discs 9, 10 are vertically offset. This serves to guide the thread being twisted and prevents it from migrating away from the twisting region. As shown in FIGURES 2 and 3, the strands 5 are each passed between the central disc 9 and their respective side discs. The central disc is rotated in one sense, anticlockwise when viewed in the direction of the arrow A and the two side discs are rotated with the same peripheral speed in the opposite sense, viewed in the same manner. The result is that for the period over which the rubber sections 11, 11a on the central disc are in contact with the strand, the strand is rolled between the contra-moving surfaces on the discs and twist is imparted to it. It will be appreciated, particularly with reference to FIGURE 5, that strands on opposite sides of the central disc will be twisted in opposite directions. Thus if it were desired to produce, in accordance with this invention, two strands having their twist zones of equal length and exactly in phase, the rubber sections 11, 11a on the central disc would need to be 180 out of phase. However, as explained above for the production of a strong yarn the twist change-over regions need to be slightly out of phase and accordingly as will be observed from FIGURE 4 the sections 11, 11a are placed only about 120 out of phase.

The twist length compensator 6 serves to compensate for changes in the length of the twisted strand due to changes in the degree of twist in the strand throughout the twisting cycle. In the form shown it consists simply of a disc 6a to which are attached pegs 6b. The discs are rotated so that the pegs 6b cyclically deflect the strand 5 in synchronism with the twisting disc 9 so that its length is varied in accordance with its degree of twist. The extent to which this compensation is required depends on the degree of twist being inserted into the strand. We have found that compensation is required where the strand is light and the twist is high but under less severe conditions compensation may not be needed,

The strands 5, after being intermittently twisted by the twister device 8 pass through a guide 13 (see FIGURES 3 and 4) to the nip of a pair of take-up rollers 14. As will be seen from FIGURES 6 and 7 they comprise essentially a pair of plastic impregnated fabric spur gears each having a V-shaped groove cut to about their pitch circle diameter. The two strands 5 are converged by the rollers 14 and after passing through the rollers 14 they twist up on one another to form a stable selftwist yarn over the free length between the rollers 14 and the take-up package 16. As previously explained the strand path is stabilised by the offsetting of the discs. The guide 13 is therefore merely a safety device to guard against accidental strand displacement and an aid to 6 initial threading. The take-up package is rotated on a spindle 17 and the yarn is cross-wound on to the package by means of a traversing guide 18.

In the alternative construction shown in FIGURES 8 to 10 the drafting unit 3 is of the roller type and the twister device is in the form of a twister tube 2% having jaws 21 which are so arranged that centrifugal forces due to the rotation of the tubes keep them closed. A cam device 22 is arranged so that intermittently the jaws are opened. As shown in FIGURE 10 the twister tube comprises a central stationary tube 23 through which the strand 5 passes and about which is rotated an outer tube 24. The outer tube carries the jaws 21 which are pivoted at 25 and weighted by means of adjustable weights 26 so that on rotation centrifugal forces cause the jaws to close. The inner tube 23 is capable of limited axial movement and is connected to arm 27 which in turn carries cam follower 28. Cam follower 28 rides on cam 29 and when it is reached by the lobed portions 30 the arm pivots about its pivot 31 and forces the tube 23 forward. This in turn forces the jaws 21 to open and thereby interrupts the twisting action. In the construction shown the twister tubes 20 cannot be placed close together and accordingly the two twisted strands cannot be converged close to the twisting position. Since, in order to preserve the twist in an alternating twist strand, it is necessary to restrain the strand and to ensure that its greatest free length is considerably less than the length of a twist zone, the strands are converged by means of a chain of rollers 33, 34 (which are preferably of the grooved gear type above described) and consequently are restrained by contact with the rollers until convergence takes place.

It must be understood that alternative twisting devices such as intermittent or reversing tubes; tapes, hyperboloidal rollers, and other forms of twisting arrangement with suitable modification to give an intermittent twisting action, may be substituted for the particular arrangements herein described and illustrated. It may also be possible to utilize the vortex twisting techniques of prior Australian Patents Nos. 224,281, 236,265, 238,109 and 23 8,260. It will also be obvious that other elements as well as the twister in the apparatus may be substituted by equivalent integers. For example, alternative drafting systems may be substituted for those shown and other forms of take-up rollers, guides, traversing and package winding, etc, can be used. It will also be obvious that in a practical production machine many units will be used. These may conveniently be arranged side by side on a frame as in conventional spinning frames.

Three types of yarn (or other thread) which can be produced according to this invention are illustrated in FIGURES 11A, 12A and 13A.

In FIGURE 11A the yarn consists of two similarly twisted strands 35, 36 which are plied with their twist zones in phase. It will be observed that over the zone A there is no plying twist in the yarn and that this changes from S twist on the left to Z twist on the right. It will also be observed that over the same zone the twist in the individual strands also changes, it being Z twist on the left and S twist on the right of the change-over zone. Thus over the zone A each of the strands and the plied structure has no twist so that this zone is a zone of weakness in the yarn. The twist distribution in FIGURE 11A is illustrated graphically in FIGURE 11B where the twist is shown on the axis OY against length on the axis OX. The line A represents the twist in the individual strands after self-twisting (both being identical) and the line B represents the twist in the plied structure, this being the sum of the amounts by which the individual strands have untwisted and proportional to the sum of the twist remaining in the two strands.

In FIGURE 12A the twist zones of the two strands are out of phase so that in the strand 35 the zone of no twist is at Q and in the strand 36 it is at 2, these zones being ,2. displaced respectively to the left and to the right of the twist change-over region A of the plied yarn structure. As is illustrated in the graph in FIGURE 12B the twist change-over zone A of the plied structure occurs where the individual strands have equal and opposite twist. In that graph the line C represents the twist in the strand 35, line D represents the twist in the strand 36 and line E represents the twist in the plied yarn structure.

It will be observed both from the drawing of the yarn itself and from the graph that in this structure there is no position at which there is no twist in the yarn when taken as a whole. At the position where there is no twist in one strand there is twist in the other and in the plied structure and where there is no twist in the plied structure there is twist in each of the strands. This phasing arrangement greatly adds to the strength of the yarn.

An alternative thread structure for avoiding convergence of the twist change-over regions is shown in FIGURE 13A. In that structure the twist zones in the two strands are alternately long and short and are complementary. Using the same symbols as in FIGURES 12A and 12B, it will 'be seen that in strand 35 the twist change regions are at 9, in the plied structure they are at A and in the strand 36 they are at E. It will be observed however that in strand 35 the region of Z twist is shorter than the region of S twist and that the reverse is the case in strand 36. This can readily be achieved, for example, merely by appropriately choosing the lengths and phasing of the twisting surfaces on the disc 9 in FIGURES l to 7. With the rotational directions shown in FIGURE 5, the rubber 11 may extend over more than 180, say 240, while the rubber 110 also extends over 240 but is 180 out of phase with the rubber 11. In this case regions having the same twist direction do, at their mid-points, exactly coincide. However, due to the fact that their lengths are different the twist change-over regions are, once again, displaced from one another. Similar results can be obtained by having the rubbers extending less than 180. For example, if the rubbers extend over only 120 the result will be, apart from a reduction in twist intensity, a simple inversion of that shown in FIGURE 13B.

The strength properties of self twist yarn vary greatly according to the phasing of the twist change-over regions in relation to the twist zone length. Within limits, at the lower orders of phase difference, the real criterion of strength is of course the separation of the twist changeover zones and not really the actual angular amount by which the zones are in or out of phase. However in a typical case for yarn constructed as shown in FIGURE 12A the relation between phase difference and yarn strength is of the form shown in the graph in FIGURE 14. In that graph strength is shown along axis OY against phase difference on axis OX. It will be seen that in the case illustrated the maximum strength is reached where the strands have their twist zones about 120 out of phase but that the strength diminishes rapidly as the phasing approaches the condition in which the zones are completely out of phase.

The following examples show the application of the invention to the production of yarn from a variety of staple fibres. The yarns were produced using the apparatus of FIGURES 1 to 7 and 8 to 10. It is to be noted that the drafting systems used were designed for use in the production of worsted yarns. Furthermore, in respect of fibres other than wool the examples were designed to study the behaviour of the fibres in the apparatus and were not necessarily such as to give maximum strength:

Example 1 Material.6064s quality Noble combing wool.

Spinning-The twisting was accomplished with a disc twisting unit of the type shown in FIGURES 1 to 7. The distance between the front drafting rollers 4 and the nip of the convergence rollers 14 was 16", and the distance between the front edge of the rubber twisting surface and the nip of the rollers 14 and /8". The disposition of the rubber on disc 9 was such that the emerging strands had zones of equal length of opposite twist and these zones were out of phase. The yarn was therefore of the type illustrated in FIGURE 12A.

A complete cycle of twist occupied a yarn length of about 9 /2"; i.e. 4%" between consecutive twist changeover regions, and the twisting efficiency of the discs was such that an average of 77 turns of twist was inserted between two neighbouring change-overs in a strand (before it self-twisted with the other strand).

The production rate of the machine was 138 yards per minute.

Yarn properties:

The yarn count was 60 tex and its strength was 5.0 gm./ tex with a coefiicient of variation (C of V) of 9%. The mean extension to break was 11% and the Uster irregularity meter gave a C of V of irregularity of 13.3%

This yarn was used for weaving.

Example 2 Mmerial.6064s quality Noble combing wool.

Spinning.The twisting was accomplished by means of twister units as depicted in FIGURES 8 to 10, the rotational speed of the twisters being 10,000 rpm. The distance between the nip of the front drafting rollers 4 and the first nip of the convergence rollers 33 was 19" and the distance between the nip of the twister jaws 21 and the first nip of the convergence rollers was /2". The two twisters were operated in phase to produce a yarn of the type shown in FIGURE 11A.

A complete cycle of twist occupied a yarn length of 9"; i.e. 4 /2" between consecutive twist change-overs. The balance of the centrifugal jaws was such that they gave rise to a twisting efiiciency high enough to give an average of 19 turns of twist between two neighbouring changeovers in a strand (before it self-twisted with the other strand).

The production rate of the machine was 26 yards of yarn per min.

Yarn pr0perties.The yarn count was 145 tex and the strength was 2.1 gm./tex with a C of V of 8%. The mean extension to break was 11%.

This yarn was used for knitting and weft insertion in weaving.

Example 3 Material.6064s quality Noble combing wool.

Spin ning.Twisting conditions were the same as for Example 2 except as follows. The two twisters were operated 72 out of phase and a complete cycle of twist occupied a yarn length of 7". The balance of the centrifugal jaws was such that they gave rise to a twisting efficiency high enough to give an average of 119 turns of twist between two neighbouring change-overs in a strand before it self twisted with the other strand.

The production rate of the machine was 4 /2, yards of yarn per minute.

Yarn pr0perties.The yarn count was 27 tex and the strength was 4.9 gm./tex with a C of V of 21%. The mean extension to break was 9.5%.

This yarn appeared to be suitable for weaving.

Example 4 Material.Terylene staple-4 denier, 4 /2" staple. (Terylene is a registered trademark.)

Spinning.Twisting conditions were the same as for Example 2 except as follows. The two twisters were operated 120 out of phase and a complete cycle of twist occupied a yarn length of 16". The balance of the centrifiugal jaws was such that they gave rise to a twisting efficiency high enough to give an average of 123 turns of twist between two neighbouring change-overs in a strand before it self-twisted with the other strand.

The production rate of the machine was 7 yards of yarn per minute.

9 Yarn properties.The yarn count was 50 tex and the strength was 26.3 gm./tex with a C of V of 15%. The mean extension to break was 26.3%.

Example Material.--Acrilan staple3 denier, 4 /2" staple.

(Acrilan is a registered trademark.)

Spinning-Twisting conditions were the same as for Example 2 except as follows. The two twisters were operated 120 out of phase to give a complete cycle of twist occupying a yarn length of /2. The balance of the centrifugal jaws was such that they gave rise to a twisting efiiciency high enough to give an average of 119 turns of twist between two neighbouring change-overs in a strand before it self-twisted with the other strand.

The production rate of the machine was 7 yards of yarn per minute.

Yarn properties.The yarn count was 57 tex and the strength was 12.4 gm./tex with a C of V of 11.0%. The mean extension to break was 19.3%.

Example 6 Material.-Bright viscose staple3 denier, 4 /2" staple.

Spinning.Twisting conditions were the same as for Example 2 except as follows: The two twisters were operated 120 out of phase to give a complete cycle of twist occupying a yarn length of 13". The balance of the centrifugal jaws was such that they gave rise to a twisting efiiciency high enough to give an average of 74 turns of twist between two neighbouring change-overs in a strand before it self-twisted with the other strand.

The production rate of the machine was 7 /2 yards of yarn per minute.

Yarn properties.-The yarn count was 95 tex and the strength was 10.7 gm./tex with a C of V of The mean extension to break was 11.9%.

Example 7 Material.Cotton-%" ordinary American type.

Spinning.Twisting conditions were the same as for Example 2 except as follows. The two twisters were operated 120 out of phase to give a complete cycle of twist occupying a yarn length of 13". The distance between the twister nips and the first nips of the convergence unit was reduced to A1". The balance of the centrifugal jaws was such that that gave rise to a twisting efficiency high enough to give an average of 88 turns of twist between two neighbouring change-overs in a strand before it selftwisted with the other strand.

The production rate of the machine was 7 /2 yards of yarn per minute.

Yarn pr0perties.The yarn count was 108 tex and the strength was 6.4 igm./tex with a C of V of 18%. The mean extension to break was 8.2%. (It should be remembered that this yarn was produced with aid of a worsted drafting system. Better results should be expected using a cotton drafting system.)

Example 8 Material.Nylon--3 denier, 4 /2" staple.

Spinning.Twisting conditions were the same as for Example 2 except as follows. The two twisters were operated 120 out of phase and a complete cycle of twist occupied a yarn length of 14 /2". The balance of the centrifugal jaws was such that they gave rise to a twisting efiiciency high enough to give an average of 102 turns of twist between two neighbouring change-overs in a strand before it self-twisted with the other strand.

The production rate of the machine was 7 /2 yards of yarn per minute.

Yarn pr0pertz'es.-The yarn count was 64 tex and the strength was 22.2 gm./tex with a C of V of 16%. The mean extension to break was 27.7%.

Example 9 Material.Acetate staple-3 denier, 6" staple. Spin=ning. Twisting conditions were the same as for Example 2 except as follows. The two twisters were operated 84 out of phase and a complete cycle of twist occupied a yarn length of 13". The balance of the centrifugal jaws was such that they gave rise to a twisting efficiency high enough to give an average of 70 turns of twist between two neighbouring change-overs in a strand before it self-twisted with the other strand.

The production rate of the machine was 9 /2 yards of yarn per minute.

Yarn pr0perties.The yarn count was 85 tex and the strength was 5.1 gm./tex with a C of V of 18%. The mean extension to break was 7.1%.

The above description in relation to the production of yarn from staple fibre has employed a nomenclature in which the input thread to the drafting means has been called roving, the twisted thread between the twister device and the output from the drafting means has been called a strand and the self-twist stabilised structure resulting from the combination of the individual strands has been called yarn. In what follows there will be discussed the production of other thread structures such as rovings in relation to which the use of the abovementioned expressions would not be appropriate in the light of the current trade usage in relation to conventional thread structures. It will be appreciated however that in the application of the invention to other thread structures the thread will pass through stages which are the equivalents of the roving, strand and yarn stages.

The above description illustrates the application of this invention to the production of yarn from staple fibres. However, there are many other applications for which we believe this invention may be used. It can, for example, be used in the production of rovings in the earlier stages of staple yarn production. This invention is also useful where special properties are desired to be introduced to a yarn by twisting procedures with or without setting such as heat setting. It is at present envisaged that the most likely further use for the invention will be in the drawing stages of the production of rovings from staple fibre.

It is known that the invention can be utilised in the production of slivers, rovings and yarns from fibres such as wool and the above examples show that yarns can successfully be formed from staple cotton and synthetic fibres. Tests have also been carried out which show that the process of this invention and the apparatus above described can be used to produce yarns from jute and flax. Stable selftwist yarns have also been produced from bulked continuous synthetic filament yarns and also from untreated continuous filament with various filaments fed to the twisting device under different and varying tensions.

It is to be understood that the invention is not limited in its application to the production of stabilised self-twist thread from only one or two intermittently twisted strands. The invention is also applicable to the production of selftwist threads combining more than two strands. This can be done by combining there or more strands during production or alternatively by splitting and recombining already formed self-twist threads each of, say, two strands to form one multi-strand self-twist thread. If the multistrand thread is to have properties similar to the threads from which it is formed the phasing of the strands should be preserved, but if required different properties can be imparted to the multi-strand thread by altering the phasing.

The invention is also useful for imparting strength to slivers produced by other machines, which are normally fed without twisting or rubbing into cans. This is particularly advantageous for slivers of low weight per unit length which would otherwise not be strong enough to be handled in a subsequent operation. One example of this application is in the Noble comb where the invention can be applied in bringing together the slivers from the two sides of the machine. A considerable reduction in sliver breaks is achieved when the sliver is subsequently withdrawn from its container. Any gilling machine of two or more heads fitted with apparatus according to the invention can now be used to produce strong slivers of very low weight per unit length.

In the application of the invention to any of these processes each sliver or roving strand is subjected to an alternating twisting operation similar to that described in relation to the production of yarn. A plurality of strands of slivers or rovings so twisted (say 2, 3 or 4) is brought together with the regions of twist suitably phased and the strands allowed to twist up on one another. The properties of the final roving or sliver assembly can be varied considerably by adjusting the phasing of the twist zones in the individual strands with respect to one another, and this adjustment can be made easily and conveniently.

In the case of the early stages of yarn production (for example, drawing) the resultant stabilised assembly of rovings may be wound on to a package. The winding on is a simple winding operation only, and the twisting or rubbing devices previously used are omitted entirely. There is no real limitation on package size and very much higher production rates are possible. It is no longer necessary to stop the machine to remove a full package. Automatic dofiing of the package can now be achieved using very simple mechanical devices, such as are known and used in yarn winding. Furthermore the take-off package can be such that it can be used as an input package for a subsequent processing machine. Automatic transfer devices can be devised to transfer the dotted package to the next machine.

Because the twist in the roving is not uniform, it may be necessary before the next processing stage to remove some or all of the twist in order to ensure the proper functioning of the drafting process. This can simply be done by splitting the assembly about one or more pegs, depending on the number of strands, so as to separate the strands and allow them to untwist. The input roving must be fed to the pegs in such a manner that no real twist is introduced. The separate strands can then be fed to separate input points of the machine or they may be brought back together in the untwisted condition and fed to one input point. In the latter case in order to remove or decrease any residual twist which may have become set into the fibres the strands can be brought together out of phase; that is, the phasing is so adjusted that the strands cannot twist together, but instead, mutually untwist each other. This can be done by causing each strand to travel a path which is suitably different in length from that of the others. For example, strands may be looped separately around freely rotating rollers of suitable circumference immediately adjacent to and after the splitting pegs.

Another application of the invention is in the production of core yarns, i.e. yarns in which an outer covering is spun around an inner core. For example, this invention could readily be employed to combine a covering of staple fibre wool or cotton in the form of one or more alternating twist strands with a core of, say, continuous filament nylon.

Novelty effects can be achieved for example by plying together, either by self-twisting or by conventional techniques, a self-twist yarn with another yarn either of a self-twist or conventional construction. Also a self-twist yarn can be produced in which one or more of the strands is a yarn of conventional structure.

There are many types of threads and many types of special effects which can be produced in yarns and in fabrics by various applications of this invention. One special fabric effect which has been produced is one which is to some extent inherent in the structure of yarn produced in accordance with this invention. Due to the fact that the twist pattern in the yarn changes along its length varying effects may be produced in cloth produced from such yarn by taking advantage of the more or less random occurrence of yarn portions of a particular twist pattern. In one fabric produced a very interesting pepper and salt pattern was obtained using a yarn formed of two strands of different colours. Alternatively or in addition each strand may itself be formed from a multicoloured roving.

Special properties can be induced into yarns by manipulation of the various parameters effecting the yarn and the basic characteristics of the raw material. We have already discussed some of the effects of colour and of the manipulation of the twist phasing. Other effects may be induced by variation of the degree of twist in and the length of the twist zones. For example one strand may have a higher degree of twist than another. Another possibility is to produce strands in which the twist lengths are not uniform, i.e. the zone length of twist in one sense may be longer or shorter than the zone length of twist in the opposite sense. A further possibility is to produce a structure in which the twist zone length varies from strand to strand. There are obviously other variations which may be made and these variations and permutations of them give great scope for the production of various types of yarn and other thread structures according to the particular effects required.

The production of twisted assemblies by the process of this invention appears to open up many possibilities in the production and treatment of yarns and fabrics made from them. The invention is to be understood therefore as being not limited by the particular applications and procedures above described but rather it is merely exemplified by them.

I claim:

1. The process for forming stable twisted threads from at least two strands comprising the steps of twisting a strand to produce alternating zones of opposite twist repeated along the length of the strand, converging said strand with another strand, and leaving the converged strands free of support along a distance of the order of at least the length of two consecutive zones of opposite twist for allowing the first-mentioned strand partly to untwist and thereby to twist about the second-mentioned strand.

2. The process for forming stable twisted threads comprising the steps of separately twisting each of at least two strands so that each strand has repeated along its length alternating zones of opposite twist separated by twist change-over regions at which there is an absence of twist, converging the twisted strands in such a way that like twist zones thereof are at least partly in phase, and leaving the converged strands free of support along a length thereof at least equal to the length of two consecutive zones of opposite twist for allowing the strands partly to untwist and thereby to twist about one another.

3. The process claimed in claim 2 wherein the strands are converged in such a way that the twist change-over regions thereof are out of phase with one another.

4-. The process claimed in claim 3 wherein all of the twist zones in each strand are of equal length and wherein the strands are converged in such a way that like twist zones are partly out of phase.

5. The process claimed in claim 3 wherein a first strand is twisted to provide relatively long zones of Z twist alternating along its length with relatively short zones of S twist and wherein a second strand is twisted so as to provide alternating zones of S twist equal in length to the zones of Z twist in the first strand and zones of Z twist equal in length to the zones of S twist in the first strand and wherein the strands are converged in such a way that zones of like twist are in phase.

6. The process claimed in claim 1 wherein at least one twisted strand is produced. from staple fibre.

7. The process for forming stable twisted threads from at least two strands comprising the steps of continuously feeding a strand between a first position and a second position, twisting the strand at an intermediate position between the first position and the second position to produce zones of opposite twist alternating along the length of the strand, converging said strand with another continuously moving strand at the second position, passing the converged strands through a free length equal to at least the length of two consecutive zones of opposite twist and there allowing the first-mentioned strand partly to untwist and thereby to twist about the second-mentioned strand.

8. The process for forming stable twisted threads comprising the steps of continuously feeding at least two strands between a first position and a second position, separately twisting each strand at an intermediate position between the first position and the second position to produce in each strand zones of opposite twist alternating along the length of the strand, and separated from one another by twist change-over regions at which there is an absence of twist, converging the twisted strands with one another at the second position in such a way that like twist zones are at least partly in phase, and passing the converged strands through a free length equal to at least the length of two consecutive zones of opposite twist and there allowing the strands partly to untwist and thereby to twist about one another.

9. The process claimed in claim 8 wherein the strands are converged in such a way that the twist change-over regions thereof are out of phase with one another.

It). The process claimed in claim 9 wherein all of the twist zones in each strand are of equal length and wherein the strands are converged in such a way that like twist zones are partly out of phase.

11. The process claimed in claim 9 wherein a first strand is twisted to provide relatively long zones of Z twist alternating along its length with relatively short zones of S twist and wherein a second strand is twisted so as to provide zones of S twist equal in length to the zones of Z twist in the first strand and zones of Z twist equal in length to the zones of S twist in the first strand and wherein the strands are converged in such a way that zones of like twist are in phase.

12. In a process for the production of yarn from staple fibre, the steps of treating a roving of staple fibre in a first processing machine, continuously feeding the roving from said first machine, twisting the roving so as to produce alternating zones of opposite twist repeated along its length, converging the roving so twisted with another similarly twisted roving in such a way that like twist zones are at least partly in phase, allowing the rovings partly to untwist and thereby to twist about one another to form a plied structure, transporting the plied structure to a second processing machine, and splitting the plied structure into its individual rovings whereby the zones of alternating twist in the individual rovings are permitted to cancel one another out.

13. Apparatus for forming stable twisted threads comprising feeding means to feed a strand between a first position and a second position, twisting means at an intermediate position between the first and second positions to impart to the strand alternating zones of opposite twist, said twisting means including a pair of contra-moving elastomeric surfaces arranged to contact the strand and to move transversely of the latter as the strand moves between said surfaces past the intermediate position, said surfaces further having a component of motion opposite to the direction of motion of the strand as it moves past the intermediate position, means to feed a second strand to the second position, means at the second position to converge the strands, and take-up means operative to take-up the converged strands and being spaced from the second position by a distance sufficient to provide a free length of the converged strands equal to at least the length of two consecutive zones of opposite twist.

14. Apparatus for forming stable twisted threads comprising feeding means to feed a strand between a first position and a second position, twisting means disposed at an intermediate position between said first and second positions and comprising a pair of contra-rotating discs arranged close together with their planes of rotation nearly parallel, annular elastomeric surfaces attached to each of said discs and adapted to contact the strand as it passes between them thereby to twist the strand, part of the elastomeric surface of at least one of the discs being cut away in order to render the twisting operation intermittent so as to produce in said strand alternating zones of opposite twist, means to feed a second strand to the second position, means at the second position to converge the strands, and take-up means spaced from said second position to take-up the converged strands, said takeup means being spaced from the second position a distance to provide a free length for the converged strands equal to at least the length of two consecutive Zones of opposite twist.

15. Apparatus as claimed in claim 14 wherein the axes of rotation of the discs are offset and the directions of rotation of the discs are arranged so that at its point of contact with the strand each elastomeric surface moves with a component of motion in the direction opposite to the direction of motion of the strand.

16. Apparatus as claimed in claim 14 wherein one of said discs is provided on each of its faces with annular elastomeric surfaces and wherein there is further provided a third disc arranged to cooperate with said one disc to impart to said second strand alternating zones of opposite twist.

17. Apparatus as claimed in claim 16, wherein the elastomeric surfaces on each of the discs are arranged so as to be at least partly out of phase.

18. The process for forming stable twisted threads from at least two strands, comprising the steps of twisting a strand to produce alternating zones of opposite twist repeated along the length of the strand, converging the twisted strand with another strand, and leaving the converged strands free of support along a distance suflicient for allowing the first-mentioned strand partly to untwist and thereby to twist about the second-mentioned strand.

'19. The process for forming stable twisted threads from at least two strands, comprising the steps of separately twisting each of at least two strands so that each strand has repeated along its length alternating zones of opposite twist, converging the twisted strands in such a way that like twist zones thereof are at least partly in phase, and leaving the converged strands free of support along a distance sufficient to allow the strands to partly untwist and thereby to twist about one another.

20. Apparatus for forming stable twisted threads comprising feeding means to feed a strand between a first position and a second position, twisting means at an intermediate position between the first and second positions to-impart to the strand alternating zones of opposite twist, means to feed a second strand to the second position, means at the second position to converge the strands, take-up means operative to take-up the converged strands and being spaced from the second position by a distance sufficient to provide a free length of the converged strands equal to at least the length of two consecutive zones of opposite twist, and compensating means disposed between said first position and the intermediate position and being operative to cyclically alter the path length of the strands passing between said first and second positions, thereby to compensate for variations in the length of the strand as it is twisted.

21. Apparatus for forming stable twisted threads comprising feeding means to feed a strand between a first position and a second position, twisting means at an intermediate position between the first and second positions to impart to the strand alternating zones of opposite twist, means to feed a second strand to the second position, means at the second position to converge the strands including at least a pair of intermeshing gears each having a circumferential groove cut to approximately the pitch circle diameter of the gear, and take-up means operative to take-up the converged strands and being spaced from the second position by a distance sufiicient to provide a free length of the converged strands equal to at least the length of two consecutive zones of opposite twist.

22. Apparatus for forming stable twisted threads comprising feeding means to feed a strand between a first position and a sceond position, twisting means at an intermediate position between the first and second positions to impart to the strand alternating zones of opposite twist, said twisting means including a rotatable twisting tube having jaws which are centrifugally closed on the strand in response to rotation of said tube and means operative intermittently to force open said jaws for interrupting the twisting action, means to feed a second strand to the second position, means at the second position to converge the strands, and take-up means operative to takeup the converged strands and being spaced from the second position by a distance sufiicient to provide a free length of the converged strands equal to at least the length of two consecutive zones of opposite twist.

References Cited by the Examiner UNITED STATES PATENTS 9/1950 Abbott 5751 X 9/1957 Trapido et a1. 57-773 10/1960 Lenk et a1. 5777.3 6/1961 Quittner 5777.4 X 7/1961 Bunting 5777.3 2/1964 Breen 5734X FOREIGN PATENTS 6/1954 France.

7/1961 France.

4/1958 Great Britain.

3/1957 Italy.

MERVIN STEIN, Primary Examiner. 

13. APPARATUS FOR FORMING STABLE TWISTED THREADS COMPRISING FEEDING MEANS TO FEED A STRAND BETWEEN A FIRST POSITION AND A SECOND POSITION, TWISTING MEANS AT AN INTERMEDIATE POSITION BETWEEN THE FIRST AND SECOND POSITIONS, TO IMPART TO THE STRAND ALTERNATING ZONES OF OPPOSITE TWIST, SAID TWISTING MEANS INCLUDING A PAIR OF CONTRA-MOVING ELASTROMERIC SURFACES ARRANGED TO CONTACT THE STAND AND TO MOVE TRANSVERSELY OF THE LATTER AS THE STAND MOVES BETWEEN SAID SURFACES PAST THE INTERMEDIATE POSITION, SAID SURFACES FURTHER HAVING A COMPONENT OF MOTION OPPOSITE 